If I were KD (and he may have already tried this), I'd just show him the video clips of his goals while at Newcastle. If there's one way to inspire confidence in a player, that's it. It's proof of what he's capable of and gives him the confidence that he's already got what it takes to perform at that level against the same opposition.
Watching those goals, he showed more passion in one goal there than he's showed in every minute he's played for us combined. The way he attacks the crosses and does whatever it takes was impeccable, his finishing was brilliant, his positioning was ten times better than what he's done for us, his runs were inch-perfect, and what kept it all together was that he had the passion and confidence that Bellamy shows.
Now, in red, he's hardly capable of striking a volley. Clearly it is a confidence issue, there is no way that he'd just forget how to hit a ball properly and I would think that if he knew what kind of runs to make (against the same oppositions mind you) and when to make them last year, he'd easily be able to do it this year. I'm not sure what it is, be it the pressure, or the players around him, or whether he's got a fitness problem, whatever it may be, he's shown that he has the capability.
Anyone who doesn't believe that, I think should take another look at his goals for Newcastle last year. If only he could start recreating those performances for us, we wouldn't need another signing, not now and not in the summer. Obviously has his ways to go given his problems on and off the field, but even though he hasn't even shown anything near a glimpse of it, he's capable of a lot on the pitch.